1. Field of the Invention
The present invention relates to an intracavitary ultrasound probe of a mechanical scan type, which is inserted into a body cavity and scans an internal organ to obtain a tomographic image thereof by transmitting and receiving ultrasound beams with reference to the internal organ, and which is equipped with a stab needle assembly (or a biopsy needle assembly).
2. Description of the Related Art
Intracavitary ultrasound probes are primarily employed in the fields of gynecology and obstetrics for the purpose of transvaginally examining intrapelvic organs, such as the vagina, the uterus, and the ovaries.
Such probes fall into two categories, namely the electronic scan type and the mechanical scan type. The construction of a mechanical scan type probe will now be described.
The mechanical scan type probe comprises an elongated body having a transducer element at the distal end and adapted for insertion into the vagina, and a handle extending from the proximal end of the elongated body in a manner to be substantially coaxial with the elongated body. A rotating shaft is rotatably supported within the body, and the distal end of this rotating shaft is mechanically coupled to the transducer element. A motor is housed in the handle, and the driving shaft of this motor is coaxially coupled to the proximal end of the rotating shaft.
With the above construction, when the motor is driven, with the elongated body inserted in the vagina, the rotating shaft is rotated and the transducer element swings or rotates. Simultaneously, the transducer element transmits ultrasound beams to the intrapelvic organs and receives the ultrasound beams reflected from them. As a result, the intrapelvic organs are sector scanned (or radially-scanned) with the ultrasound beams, and an ultrasonic tomogram of the intrapelvic organs is displayed on a monitor.
In some cases, a stab needle assembly is fitted to the intracavitary ultrasound probe, mainly for removing an ovum from the ovary. The stab needle assembly comprises an elongated, hollow stab needle (which is like the needle of an injector), and a stab needle guide which is coupled to the elongated body of the probe and extends in parallel thereto for the guiding of the stable needle. A syringe for sucking an ovum is coupled to the proximal end of the stab needle.
The stab needle assembly is used, e.g., for a sterile woman whose oviduct connecting the uterus to the ovaries is clogged. That is, it is used for removing an ovum from the ovary, for extracorporeal fertilization, and for returning the fertilized ovum to the ovary. More specifically, the operator inserts a probe equipped with the stab needle assembly into the vagina while holding the handle of the probe. The ovary or the like is scanned with ultrasound beams, and an ultrasound tomographic image of the ovary or the like is displayed on a monitor. While observing the tomographic image on the monitor, the operator inserts the tip end of the stab needle into the ovary. By producing suction by use of the syringe coupled to the proximal end of the stab needle, the ovum is removed from the ovary and sucked into the syringe. After the ovum is fertilized extracorporeally, it is returned to the ovary by following similar procedures.
In some cases, the stab needle assembly is used for removing a tissue of a tumor which may grow in the vagina, so as to judge whether or not the tumor is malignant.
In the case of the conventional probe, the elongated body and the handle are substantially coaxial, and the stab needle guide extends in parallel to the elongated body. Since, therefore, the proximal end of the stab needle and the handle are located close to each other, the region around the proximal end of the stab needle does not provide a sufficiently wide space needed for reliably operation of the stab needle. In addition, a syringe cannot be easily attached to the proximal end of the stab needle.
Conventionally, these problems have been solved by attaching the stab needle guide slantwise with reference to the elongated body. With this construction, a sufficiently wide space is provided between the handle and the proximal end of the stab needle, so that it is possible both to reliably operate the stab needle and to easily attach the syringe to the proximal end of the stab needle. However, this construction is disadvantageous, in that the distance between the proximal end of the stab needle guide and that of the elongated body is comparatively long. Therefore, when the stab needle assembly and the probe are inserted into the vagina of the patient, the proximal end of the stab needle guide is pressed against the vaginal wall, causing pain to the patient.
During the examination, the operator may feel it necessary to rotate the scan plane, so as to obtain tomographic images in various directions. For this purpose, the operator tries to rotate the probe around its longitudinal axis, but this cannot be easily done if the proximal end of the stab needle guide is pressed against the vaginal wall. In addition, the patient suffers much pain when the probe is being rotated by the operator.
The operator may also feel it necessary to tilt the scan plane, so as to obtain various tomographic images. For this purpose, the operator tries to tilt the probe in a manner to move the distal end of the probe. However, the tilting angle is limited if the proximal end of the stab needle guide is pressed against the vaginal wall, and the patient suffers much pain in this case as well.